It takes a while to spot what’s sci-fi about Black Mirror’s best episode

"Black Mirror" is known for dystopian visions of our tech-enhanced future. The episode everyone is talking about, though, is different.

"San Junipero" is the fourth episode of the Netflix-produced third season of the short film series.

Put it on and you may be struck, first, by the retro feel. Second, you may wonder what is sci-fi about it: the first act features no world-changing tech, only subtle hints in dialogue, music, and scenery that there's more than meets the eye. Finally, the ending is unlike any other in the series.

We've pulled highlights from the opening below. See if you can tell what's going on.

Moments later in a club, Kelly sits down next to Yorkie to try to lose that guy. "Go along with whatever I say," Kelly says.

The two women get a drink. Kelly says she likes Yorkie’s glasses: "People try so hard to look how they think they should look. They probably saw it in some movie. But I like these. They’re authentically you."

Yorkie lasts about 20 seconds on the dance floor before running outside.

From "Black Mirror" San Junipero

Kelly joins her: "Sorry I pushed you into it," she says. "Saturday night’s once a week. It’s like no time. I get impatient."

From "Black Mirror" San Junipero

Yorkie says everyone was looking at them—two girls dancing. Kelly tells her people are less uptight than they used to be. Yorkie confesses that she’s never been on a dance floor before, that she never does anything fun, and that she is engaged.

From "Black Mirror" San Junipero

But her fiancé isn’t here. "Wanna go to bed with me?" Kelly asks. "We could be back at mine in like [snap]."

From "Black Mirror" San Junipero

Yorkie, clearly torn, says she can’t.

From "Black Mirror" San Junipero

Yorkie walks alone in the rain.

From "Black Mirror" San Junipero

The camera pans down to a full moon in a puddle and cuts.

From "Black Mirror" San Junipero

The show jumps forward in time.

From "Black Mirror" San Junipero

13 minutes have passed, and we still have almost no idea what’s going on. Yet there's an engaging story and something mysterious happening. As the show continues, we see how radically different this world is from ours—yet how realistic it might be.

From "Black Mirror" San Junipero

The other unusual thing about this episode? It's got an optimistic ending.

"I really wanted to create something that felt different from what we’re used to at the moment, and I think that’s what’s really refreshing about it," director Owen Harris told The Hollywood Reporter. "It’s this world where you’re allowed to dance around to Belinda Carlisle, it’s a world of guilty pleasures but, because of the look and the feel of it, it’s larger than life, which makes everything a little bit more optimistic."